This invention relates generally to improvements in an automatic coupling device for use in a fluid circuit, and more particularly to a quick disconnect hydraulic line coupler actuated by a cam to permit closing off of the flow through the coupler so that the coupling parts can be isolated from any hydraulic pressure present on the lines during coupling or decoupling operation, and which also permits closing off the flow even when the coupling parts are still coupled together physically.
Many hydraulic couplers in the past have included quick disconnect features and some have even included shut-off valves. For example, U.S. Pat. No. 2,675,829 shows a quick disconnect coupling made with a selectively operated shut-off valve. Other couplers of this general type are shown in the U.S. Pat. No. 2,675,829, U.S. Pat. No. 3,129,919, and U.S. Pat. No. 2,625,410.
Further, a hydraulic coupler which has a shut-off feature of this general type is shown in U.S. Pat. No. 3,710,823. However, in this prior patent, the internal valves could be unintentionally opened under hydraulic line pressure during the act of nipple connection.